1/*
2 * AVR power-management chip interface for the Buffalo Linkstation /
3 * Kurobox Platform.
4 *
5 * Author: 2006 (c) G. Liakhovetski
6 * g.liakhovetski@gmx.de
7 *
8 * This file is licensed under the terms of the GNU General Public License
9 * version 2. This program is licensed "as is" without any warranty of
10 * any kind, whether express or implied.
11 */
12#include <linux/workqueue.h>
13#include <linux/string.h>
14#include <linux/delay.h>
15#include <linux/serial_reg.h>
16#include <linux/serial_8250.h>
17#include <linux/of.h>
18#include <linux/of_address.h>
19#include <asm/io.h>
20#include <asm/termbits.h>
21
22#include "mpc10x.h"
23
24static void __iomem *avr_addr;
25static unsigned long avr_clock;
26
27static struct work_struct wd_work;
28
29static void wd_stop(struct work_struct *unused)
30{
31 const char string[] = "AAAAFFFFJJJJ>>>>VVVV>>>>ZZZZVVVVKKKK";
32 int i = 0, rescue = 8;
33 int len = strlen(string);
34
35 while (rescue--) {
36 int j;
37 char lsr = in_8(avr_addr + UART_LSR);
38
39 if (lsr & (UART_LSR_THRE | UART_LSR_TEMT)) {
40 for (j = 0; j < 16 && i < len; j++, i++)
41 out_8(avr_addr + UART_TX, string[i]);
42 if (i == len) {
43 /* Read "OK" back: 4ms for the last "KKKK"
44 plus a couple bytes back */
45 msleep(msecs: 7);
46 printk("linkstation: disarming the AVR watchdog: ");
47 while (in_8(avr_addr + UART_LSR) & UART_LSR_DR)
48 printk("%c", in_8(avr_addr + UART_RX));
49 break;
50 }
51 }
52 msleep(msecs: 17);
53 }
54 printk("\n");
55}
56
57#define AVR_QUOT(clock) ((clock) + 8 * 9600) / (16 * 9600)
58
59void avr_uart_configure(void)
60{
61 unsigned char cval = UART_LCR_WLEN8;
62 unsigned int quot = AVR_QUOT(avr_clock);
63
64 if (!avr_addr || !avr_clock)
65 return;
66
67 out_8(avr_addr + UART_LCR, cval); /* initialise UART */
68 out_8(avr_addr + UART_MCR, 0);
69 out_8(avr_addr + UART_IER, 0);
70
71 cval |= UART_LCR_STOP | UART_LCR_PARITY | UART_LCR_EPAR;
72
73 out_8(avr_addr + UART_LCR, cval); /* Set character format */
74
75 out_8(avr_addr + UART_LCR, cval | UART_LCR_DLAB); /* set DLAB */
76 out_8(avr_addr + UART_DLL, quot & 0xff); /* LS of divisor */
77 out_8(avr_addr + UART_DLM, quot >> 8); /* MS of divisor */
78 out_8(avr_addr + UART_LCR, cval); /* reset DLAB */
79 out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO); /* enable FIFO */
80}
81
82void avr_uart_send(const char c)
83{
84 if (!avr_addr || !avr_clock)
85 return;
86
87 out_8(avr_addr + UART_TX, c);
88 out_8(avr_addr + UART_TX, c);
89 out_8(avr_addr + UART_TX, c);
90 out_8(avr_addr + UART_TX, c);
91}
92
93static void __init ls_uart_init(void)
94{
95 local_irq_disable();
96
97#ifndef CONFIG_SERIAL_8250
98 out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO); /* enable FIFO */
99 out_8(avr_addr + UART_FCR, UART_FCR_ENABLE_FIFO |
100 UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT); /* clear FIFOs */
101 out_8(avr_addr + UART_FCR, 0);
102 out_8(avr_addr + UART_IER, 0);
103
104 /* Clear up interrupts */
105 (void) in_8(avr_addr + UART_LSR);
106 (void) in_8(avr_addr + UART_RX);
107 (void) in_8(avr_addr + UART_IIR);
108 (void) in_8(avr_addr + UART_MSR);
109#endif
110 avr_uart_configure();
111
112 local_irq_enable();
113}
114
115static int __init ls_uarts_init(void)
116{
117 struct device_node *avr;
118 struct resource res;
119 int len, ret;
120
121 avr = of_find_node_by_path(path: "/soc10x/serial@80004500");
122 if (!avr)
123 return -EINVAL;
124
125 avr_clock = *(u32*)of_get_property(node: avr, name: "clock-frequency", lenp: &len);
126 if (!avr_clock)
127 return -EINVAL;
128
129 ret = of_address_to_resource(dev: avr, index: 0, r: &res);
130 if (ret)
131 return ret;
132
133 of_node_put(node: avr);
134
135 avr_addr = ioremap(offset: res.start, size: 32);
136 if (!avr_addr)
137 return -EFAULT;
138
139 ls_uart_init();
140
141 INIT_WORK(&wd_work, wd_stop);
142 schedule_work(work: &wd_work);
143
144 return 0;
145}
146
147machine_late_initcall(linkstation, ls_uarts_init);
148

source code of linux/arch/powerpc/platforms/embedded6xx/ls_uart.c